Textile industry
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| Cohort | 6,242 male cotton textile workers in Georgia, US during 1948–1951 Follow-up: 1948–1963 | 7 | Identified from the national registry using ICD-7 | US general white male population | Industry | Age, sex, race | Overall: SMR = 27.3 | Authors attributed the low rate to a HWE |
Henderson and Enterline [ 1] | Cohort | Cohort 1: 5,822 men working during 1938–1941 Follow-up: 1938–1963 Cohort 2: 6,242 men working during 1948–1951 Follow-up: 1948–1963 All cotton textile workers in Georgia, US | Cohort 1: 36.5 Cohort 2: 26.4 | Identified from the national registry using ICD-7 | General white male population of Georgia, US | Industry, duration (1,772 workers who work in both 1938–1951 and 1948–1951 periods with >10 years of exposure and the remaining 4,936 from cohort 1 and 5,356 from cohort 2) | Age, sex, race | SMRs: Overall: Cohort 1: 54.8 Cohort 2: 30.3 Duration: Cohort 1: 65.3 Cohort 2: 20.5 Worked in both periods: 42.4 | Authors considered external data that showed no differences in smoking habits between textile workers and the general population and suggested that “something” in the working environment protects cotton textile workers from cancer |
| Cohort | 116,060 male and 51,415 female textile workers. All aged 14–60 from the Prato area, Italy. Comparison: The general population of Prato (79,697 males and 162,545 females) Follow-up: 1970–1974 | 45 | Identified from death certificates and confirmation through family interviews | The mean of the census data of the years 1961–1971 | Industry, tasks (four categories: selection of raw material, dyeing, spinning, weaving) | Age, sex | Textile workers: Men: MR = 365 Women: MR = 5.8 Control population: Men: MR = 18.8, Women: MR = 1.2 Tasks: MR = 191.5, 118.9, 28.3, and 21.9 for selection of raw material, dyeing, spinning, and weaving, respectively | Authors suggested that there is a link between some occupational tasks and lung cancer |
Merchant and Ortmeyer [ 60] | Cohort | 2,119 men and 725 women in North Carolina, US. Analysis restricted to 1,113 men and 393 women with job histories Follow-up: 1940–1975 | 18 | Identified from death certificates using ICD-8 | US general population | Four job categories by exposure to cotton dust (preparation, yarn processing, slashing/weaving, other), duration of employment | Age, sex, race | Overall: SMR = 74 among white males. Preparation (SMR = 52), yarn processing (SMR = 30), slashing/weaving (SMR = 79), other (SMR = 174), p < 0.05 for all | Authors concluded that methodological issues like a HWE and different smoking habits were responsible for underestimating the cohort’s SMRs |
| Cohort | 3,458 British cotton industry workers Follow-up: 1968–1984 | 42 | Identified from the national registry using ICD-8 and ICD-9 (depending on the period of death) | England and Wales general population | Industry, duration (<15, 15–29, >29 years) | Age, sex, smoking | SMRs: Overall: males: 0.75 (0.51–1.06), females: 0.79 (0.39–1.41). Duration: men: 127, 78, 63. Women: 0, 127, 65 for <15, 15–29 and >29 years, respectively (p > 0.05 for all). Nonsmokers: male: 12, female: 13 (p < 0.05 for both). Smokers: male = 97 female = 160 (p > 0.05) | Authors concluded that the deficit in lung cancer could not be explained from differences in smoking habits and suggested that their results support the proposed protective effect of endotoxin on the development of lung cancer |
| Cohort | 1,065 women hired between 1950 and 1971 by 5 Finnish cotton mills. Follow-up: 1950–1985 | 3 | Identified from death certificates using ICD-8 | The general Finnish female population in 1977 | Industry | Age, sex | SMR = 158 (p > 0.05) | Authors reported inconsistency with previous studies |
Szeszenia-Dabrowska et al. [ 62] | Cohort | 2,949 men and 4,943 women with at least 10 years of work in the Lodz (Poland) cotton plants. Follow-up: 1964–1993 | 140 | Identified from the related registry using ICD-9 | General Polish population | Industry, department (4 categories: chemical processing, weaving, spinning, other), duration | Age, sex | SMRs: Overall: men: 0.89 (71–110), women: 0.55 (0.28–0.96). Department: men: 0.83 (0.44–1.42), 0.79 (0.50–1.20), 0.85 (0.49–1.38), 1.02 (0.71–1.43) and women: 0 (0–0), 0.82 (0.37–1.56), 0.13 (–), 0.84 (0.10–3.03) for the 1st, 2nd, 3rd, and 4th departments, respectively | Authors focused on causal factors that showed elevated risks and attributed the decreased results in females to a HWE. However, they also reported consistency with previous regarding the results for lung cancer |
| Cohort | 267,400 women born between 1925 and 1958 employed in 526 factories in the Shanghai textile industry Follow-up: 1989–1998 | 236 | Identified from the Shanghai cancer registry using ICD-9 | Shanghai general female population | Industry and 9 major textile sectors according to the material processed and the working task | Age, sex | SIR = 0.8 (0.74–0.86) for the hole, SIR = 0.72 (0.63–0.82) for cotton spinners, weavers and knitters | No conclusion was made since the study aimed to guide future research |
| Cohort | 7,679 (4,039 men and 3,640 women) textile workers joined the textile union of Australia before 1996 Follow-up: 1982–1997 | 2 | Identified from the National cancer statistics clearing house using ICD-9 | General population of Australia | Industry | Age, sex | Men: no deaths from lung cancer. Women: SIR = 106 (12–381) | Authors reported a very small number of lung cancer deaths and thus consistency with the results of a meta-analysis study |
| Cohort | 5,495 men and 9,155 women employed for at least 1 year during 1969–1997 to the Alytus (Lithuania) factory. Follow-up: 1978–1997 | 53 | Identified from the National registry using ICD-9 | General Lithuanian population | Industry, department (1 category including spinning and weaving), duration (<10, >10 years) | Age, sex | Overall: SIR = 1.35 (0.99–1.81) for men and SIR = 1.11 (0.48–2.19) for women. Spinners/weavers: SIR = 1.12 (0.65–1.79) for men and SIR = 3.26 (0.50–3.58) for women. Deficits in SIR with increased years of work | Authors attributed the inconsistency with previous studies regarding lung cancer to unmeasured factors, low number of cases and to the multifactorial nature of carcinogenesis |
| Cohort | All economically active Finns born between 1906 and 1945 who participated in the census of 1970 (667,121 men, 513,110 women). Follow-up: 1971–1995 | 270 | Identified from the National registry using ICD-10 | All the economically active population of Finland | Dust estimates obtained from the Nordic classification of Occupations (FINJEM). Exposure to textile dust was categorized as follows: none, low (<5mg/m3-year), medium (5–20mg/m3-year), and high (>20mg/m3-year) | Age, sex, social class, smoking | Textile dust: Men: SIR = 1.00 (0.99–1.01), 1.08 (0.92–1.26), 0.87 (0.69–1.08), 0.66 (0.43–0.97) and women: SIR = 1.01 (0.98–1.05), 0.99 (0.80–1.21), 0.79 (0.66–0.95), 0.60 (0.36–0.94) for the none, low, medium, and high groups of exposure, respectively | Authors concluded that their results supported the hypothesis that exposure to textile dust decreases the risk of lung cancer and that the stronger protective effect found in the highest exposure categories add to the hypothesis that endotoxin is responsible |
Kuzmickiene and Stukonis [ 64] | Cohort | 5,495 men and 9,155 women employed for at least 1 year during 1969–1997 to the Alytus (Lithuania) factory. Follow-up: 1978–2002 | 85 | Identified from the National registry using ICD-9 | General Lithuanian population | Industry, department (cotton textile production unit; cotton textile finishing unit; maintenance unit), duration (<10, >10 years) | Age, sex | Men: SIR = 0.94 (0.73–1.19), Women: SIR = 1.36 (0.76–2.25) SIRs for the low, medium, high and very high level of cumulative exposure were 1.91 (0.92–3.51), 1.30 (0.52–2.69), 0.77 (0.21–1.96), and 0.24 (CI 0.03–0.86), respectively An average level of exposure to textile dust was assigned to the four quartiles: low exposure (>0 to <8.0 mg/m3-year), medium exposure (from 8.1 to 19.7 mg/m3-year), high exposure (from 19.8 to 64.7 mg/m3-year), very high exposure (from 64.8 to 200.6) and no exposure Employed ≥10 years: SIR = 0.89 (0.57–1.31) for men; 1.27 (0.34–3.24) for women | Authors conclude that their results confirm the lower risk of lung cancer in the cotton textile production workers compared with that in the general population. They acknowledge limitations of their study, including lack of detailed exposure records and a lack of cases |
| Cohort | Italy M/F: 3,961 Follow-up: 1970–1994 | 36 | Identified from death certificates and coded according to ICD-9 | Regional population of Veneto, Italy | Duration (tertiles), department (working with carding (with high exposure), with spinning or weaving (with lower exposure to endotoxin)) | Age, sex | Overall SMR = 1.03 (0.72–1.43). SMR was 0.93 (CI: 0.45 to 1.72; n = 10) and 1.07 (0.70 to 1.57; n = 26) for carders and non-carders, respectively. Statistically significant trend (p < 0.05) for linear decrease in risk with increasing duration of employment | Authors conclude that the study supports earlier findings that cotton workers exposed to high levels of endotoxin-containing dust for prolonged periods of time have a lower risk of lung cancer |
Astrakianakis et al. [ 67] | Case–cohort | 641 cases and 3,188 controls. Cohort population: 267,400 women born between 1925 and 58 from 526 textile factories in Shanghai. Follow-up: 1989–1998 | – | Identified from the Shanghai cancer registry using ICD-9 | Randomly selected from the cohort population | Duration, quintiles, and quartiles of exposure based on cumulative exposure derived from modeled cotton dust exposure estimates that were converted into endotoxin using previously measured job-specific endotoxin estimates. Reference: the unexposed | Age, sex, smoking | Inverse dose–response trends for the risk of lung cancer with both increased cumulative exposure (unlagged) to endotoxin and time of exposure were observed e.g., HR = 1.06 (0.79–1.41), 0.98 (0.73–1.30), 0.79 (0.58–1.06), 0.88 (0.66–1.16), 0.70 (0.52–0.95) for the 1st, 2nd, 3rd, 4th, and 5th quintile, respectively for the whole follow-up period | Authors concluded that long-term and high-level exposure to endotoxin, compared with no exposure, is associated with a reduced risk of lung cancer and suggested that their results which are supported from other studies, show that endotoxin exposure has a protective effect on the development of lung cancer |
| Case–control | 499 (25 exposed to cotton) lung cancer cases and 920 controls. All incidence male cases aged 35–70 selected from 19 hospitals of Montreal, Canada | – | Histologically confirmed identified from the hospitals’ pathology department records | Patients with other types of cancer selected from the same database | Industry (exposure to specific types of dust in two levels: non-exposed and substantially exposed) | Age, social, and economical status, race, smoking, accuracy of job history | Overall for cotton dust: OR = 0.8 (0.4–1.3) | Authors were looking for potential carcinogens and thus did not comment the non-significant inverse associations between cotton dust and lung cancer |
| Case–control | 1,495 (169 textile workers) cases and 1,495 (241 textile workers) randomly controls aged 35 to 69 from Shanghai, China selected during 1984–1985 | – | Identified from the local registry using ICD-9 and reviewed by physicians | Randomly selected from the local area population | Industry, duration, 5 major task categories and self-determined exposure to textile dust. Comparison with non-textile workers (ref.) | Age, sex, smoking | Overall: OR = 0.7 (0.6–0.9). Tasks: OR = 0.8 (0.5–1.3), 0.8 (0.5–1.2), 1.0 (0.4–2.4), 0.3 (0.1–1.3), 1.1 (0.3–3.7) for preparers, weavers, dyers, mechanics and others. Decreased risk by increased years of exposure | Authors suggested that their results were not confounded by smoking and reported that the reduced risk of lung cancer in remains unclear due to the absence of info on dose–response relationships |
| Case–control | 733 (89 textile workers) lung cancer cases and 760 (128 textile workers) controls. All men aged 35–64 from Shanghai, China | – | Identified from the local registry using ICD-9 | Randomly selected from the local population | Industry, duration (<10, 10–19, 20–29, >30 years), occupation (1 category: textile, knitting, printing and dyeing workers) | Age, sex, smoking | Overall: OR = 0.7 (0.5–1.0) Duration: OR = 0.9, 0.5, 0.9, 0.6 for <10, 10–19, 20–29, >30 years of employment, respectively. Textile, knitting, printing and dyeing workers: OR = 0.7 (0.5–1.2) | Authors reported consistency with previous studies and concluded that the low rates of lung cancer could not be due to differences in smoking habits |
| Case–control | 1,049 (31 textile workers) cases and 960 (44 textile workers) controls. All women aged 29–70 from Shenyang and Harbin, China | – | Identified from the local registries, reviewed and confirmed by physicians | Randomly selected women from the general populations of the same cities | Industry, occupation (1 category including knitters, printers, and dyers), duration (<11, >11 years). All other workers used as reference | Age, sex, smoking, study area, education | Industry: OR = 0.7 (0.4–1.1). Duration: OR = 1.0 (0.4–2.5) and OR = 0.5 (0.3–1.0) for <11 and >11 years. Occupation: OR = 0.6 (0.3–1.0). Duration: 0.7 (0.3–1.8) and OR = 0.5 (0.2–1.0) for <11 and >11 years, respectively | Authors reported that the results are consistent with previous studies but also mentioned that the reasons for the decreased risks are unknown |
| Case–control | 4,806 male and 3,595 female cases and 14,685 male and 13,010 female controls from Tianjin, China | – | Identified from the local cancer registry using ICD-9 | Patients with other types of cancers selected with the same method | Industry. Reference: all other industries | Age, sex | OR = 0.86 (0.76–0.97) for men textile workers (339 cases, 1,171 controls). OR = 1.01 (0.86–1.18) for women textile workers (226 cases, 879 controls) | The Authors reported that the decreased risk was inconsistent in literature and suggested this to be a result of differences in the raw material and composition of the cotton dust |
| Case–control | 686 (93 textile workers) cases and 712 (113 textile workers) controls, all German women | – | Histologically and/or cytologically confirmed | Randomly selected from the local population | Occupation, industry | Age, region, smoking, time since smoking cessation | Textile workers: OR = 0.7 (0.50–0.99). Leather and textile industry: OR = 0.8 (0.57–1.10) | Due to the large number of occupations included, authors focused on causal factors that showed elevated risks |
| Case–control | 474 (8 exp. to cotton) men and 66 (6 exp. to cotton) women lung cancer cases and 453 (4 exp. to cotton) men and 129 (9 exp. to cotton) women controls. All from 88 hospitals of Leningrad, Russia | – | Pathologically diagnosed lung cancer cases identified from the central pathology laboratory autopsy records | Deceased subjects with autopsy based diagnosis of non-cancer and non-smoking-related diseases | Industry (type of dust), duration (<10, >10 years), Average intensity (below or above 75% of the related MAC), cumulative exposure score (2 levels: <5 and >5 calculated as the product of average intensity score per total duration) | Age, sex, smoking, region of residence | Cotton dust: Men: Overall: OR = 2.43 (0.67–8.82), duration: OR = 10.10 (1.02–100.2) and 0.65 (0.10–4.10) for <10 and >10 years, respectively. Average intensity: OR = 4.04 (0.67–24.4) and 1.32 (0.21–8.10) for <75% and >75% MAC, respectively. Cumulative exposure: OR = 0.23 (0.03–2.17) for >5. Women: Overall: OR = 1.34 (0.42–4.22) | Authors related their results to the increased risk observed among subjects exposed to cotton dust to the high lung cancer rates among textile workers reported in other previous investigations |
Delzell and Grufferman et al. [ 27] | Proportionate mortality study | 42,355 deaths (4,462 textile workers) of white women in North Carolina (NC), US. Surveillance period 1976–1978 | 106 | Identified from the North Carolina, US DHR using ICD-8 | The proportion of deaths due to the same cause among all other NC white women decedents | Industry | Age, sex, race | Overall: 0.9 (0.7–1.0) | Authors made no comments on lung cancer mortality |
| Proportionate mortality study | 354,845 (73,394 with occupational history) deaths of women from England and Wales, aged 15–74. Surveillance period 1970–1972 | 74 | Identified from the National registry using ICD-8 | The proportion of deaths due to the same cause among all women in 1970–1972 | Occupation: five categories: (1) Fiber preparers, (2) spinners, processors, (3) laborers, (4) Winders, reelers, etc., and (5) Weavers | Age, sex | PMR = 59, 107, 34, 55, 59, 71 for Fiber preparers, spinners, processors, laborers, winders, and weavers, respectively. p < 0.01 only for weavers | Authors did not comment the low PMR for lung cancer among textile workers |
| Proportionate mortality study | 45,482 deaths (6,113 textile workers) of males from the Rhode island. Surveillance period: 1968–1978 | 307 | Identified from the local registry using ICD-8 | Deaths due to the same cause in all non-textile occupations | Industry | Age, sex | PMR = 80 (72–88) | Authors reported consistency and attributed the low rates to smoking differences |
O’Brien and Decoufle [ 30] | Proportionate mortality study | 311 white male carpet and textile workers in 5 northwest Georgia, US counties Surveillance period: 1970–1984 | 138 | Identified from mortality records of the Georgia Department of Human Resources | 38,062 deaths of the general state population during the same period | Industry | Age, sex, race | PCMR = 1.0 (0.9–1.1) | Authors reported inconsistency with previous studies |
Agriculture industry
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| Cohort + Proportionate mortality study | 21,101 deaths of white males (6,402 farmers) in Iowa, US Follow-up: 1971–1978 | 1,466 | Identified from death certificates using ICD-? | SMR: White Iowa male population PMR: Deaths of males in all non-farming occupations | Occupation | Age, sex, race | SMR: 0.84 (p < 0.01) PMR = 0.78 (p < 0.01) | Authors attributed the lower rates of lung cancer among farmers to differences in smoking habits among farmers and non-farmers and to a HWE |
| Cohort | 317,517 male and 36,711 female Swedish farmers identified from the 1960 census. Follow-up: 1961–1973 | 934 | Identified from the National cancer registry using ICD-7 | General population of Sweden | Occupation | Age, sex | SMR = 0.39 (0.36–0.43) for the total population. SMR = 0.38 for men | Authors attribute the low rates to light lifestyle and lower smoking |
Wiklund and Steineck [ 73] | Cohort | 254,417 male farmers and 1,725,845 men working in other than farming occupations, all Swedish born between 1891 and 1940. Follow-up: 1961–1979 | 1155 | Identified from the National cancer registry using ICD-7 (excl. cancer in the pleura) | The 1,725,845 men working in other than farming occupations | Occupation | Age, sex | RR = 0.36 (0.34–0.38) | Authors suggested that smoking differences cannot explain the lower risks of lung cancer experienced by framers and that probably other carcinogens are responsible for them |
Rafnsson and Gunnarsdottir [ 86] | Cohort | 5,923 male Icelandic farmers registered in the Farmers pension fund during 1977–1984. Follow-up: 1977–1985 | 15 | Identified from the National statistical registry using ICD-7 | General Icelandic male population | Occupation | Age, sex | SMR = 0.53 (0.30–0.87) | Authors attributed the lower mortality rate to the lower smoking among farmers and to the higher mortality of cancer experienced in large cities |
| Cohort | 18,811 NY farm Bureau members (>18 year old), registered for at least 1 year in the registry during 1973–1979 Follow-up: 1973–1983 | 103 | Identified from the local registry using ICD-9 | 747,128 men from the rural areas of the NY state aged >25 | Occupation | Age, sex | Overall: SIR = 52.4 p < 0.01 | Authors attributed the low rates of lung cancer to a HWE and to the lower smoking and alcohol consumption of farmers compared to the gen. population |
Gunnarsdottir and Rafnsson [ 81] | Cohort | 5,922 male Icelandic farmers registered in the Farmers pension found during 1977–1983 Follow-up: 1977–1987 | 20 | Identified from the national cancer registry using ICD-7 | General Icelandic male population | Occupation | Age, sex | SIR = 0.41 (0.27–0.59) | Authors reported consistency with previous studies and attributed the lower mortality rate to the lower smoking and lifestyle differences between farmers and the gen population |
| Cohort | 4,580 male farmers from 13 municipalities in the provinces of Bologna, Modena, and Ferrara, Italy Follow-up: 1974–1987 | 65 | Identified from the municipality records using ICD-9 | (1) The national and (2) the regional general male population | Occupation | Age, sex | (1) With regional population as reference: SMR = 61 (47–77), (2) with national population as reference: SMR = 68 (52–87) | Authors reported consistency and mentioned that their results might be relatively light tobacco consumption, type of pesticides used |
| Cohort + Mortality odds ratio analysis | Cohort: Farmers of both sexes, 15–74 years old, identified from the Danish Occupational Cancer registry. Follow-up: 1970–1980. Mortality odd ratio analysis: Farmers of both sexes aged 18–74 years, identified from the 1981 Italian census | Cohort 1: 810 MOR analysis: 188 | (1) Identified from the Danish Cancer Register using ICD-7 and (2) Record linkage between death certificates and the 1981 census classification using ICD-9 | (1) All persons economically active in 1970 (2) Subjects dying from all other causes of death were used as referents | Occupation, type of employment [two main categories: self-employed (SE) and employees (E), for Danish women 1 extra category: family worker (FM)] | Age, sex | (1) Cohort: Men: SMR = 0.40 and SMR = 0.72 for SE and E, respectively. (p < 0.05 for both). Women: SMR = 0.24, 0.45, 0.68 for SE, FW and E, respectively. (p < 0.05 for all). 2) MOR analysis: Men: MOR = 0.64 (p < 0.05) and MOR-0.84 for SE and E, respectively. Women: MOR = 0.91 and MOR = 2.12 for SE and E, respectively (p > 0.05 for both) | Authors attributed the lower rates among farmers to the lower levels of alcohol consumption and smoking among farmers |
| Cohort | 1,701 male and 426 female farmers from Aprilia, Italy Follow-up: 1972–1988 | 42 | Identified from the regional registry using the ICD-8 | General population of Italy | Occupation | Age, sex | Males: SMR = 1.02 (0.73–1.38). Females not calculated due to only one death | Authors reported inconsistency with previous studies and concluded that confounding by smoking could not explain the results |
| Cohort | 50,682 Swedish women reporting in the 1970 census who worked >20 h per week in agriculture Follow-up: 1971–1987 | 94 | Identified from the National registry using ICD-7 | General Swedish female population | Occupation | Age, sex | SIR = 0.46 (0.37–0.57) | Authors concluded that smoking could not be responsible for the low risks and suggested that physical activity might have played a role in the origin of lung cancer |
| Cohort | 2,283 male cattle and crop/orchard farmers from two areas in the province of Padova Follow-up: 1970–1992 | 39 | Identified from the local registry using ICD-9 | General male population of the region | Occupation, 2 types of farming (diary, crop), duration (12–74, 75–146, 147–248, and 249–587 months), size of farm (2–6, 7–11, 12–20, and 21–150 fields) | Age, sex, smoking | Diary farmers: overall SMR = 0.49 (0.31–0.74). Duration: SMR = 0.96 (0.41–1.89), 0.48 (0.19–0.99), 0.40 (0.13–0.93), and 0.25 (0.05–0.73) for the 1st, 2nd, 3rd, 4th quartiles. Farm size: SMR = 0.89 (0.46–1.56), 0.37 (0.12–0.86), 0.41 (0.11–1.05), 0.19 (0.02–0.69) for the 1st, 2nd, 3rd, 4th quartiles. Crop farmers: No significant associations | Authors concluded that the demonstrated decreased associations could not be attributed to a HWE and/or to confounding by smoking and suggested that their results were a result of endotoxin exposure since the protective effect was only found among diary farmers |
| Cohort | 119,681 male and 85,151 women farmers registered on 31 December 1978 in the Finish Farm register. Follow-up: 1979–1993 | 2,601 | Identified from the national registry using ICD-? | General Finish population | Occupation, 6 types of farming: Crop, small diary, diary, pig, poultry, and other farmers | Age, sex | Men: overall: SIR = 0.68 (0.66-0.71), Crop: 0.7, small diary: 0.7, Diary: 0.5, Pig: 0.5, Poultry: 0.5, Other: 0.8, all significant. Women: overall: SIR = 0.53 (0.45–0.62), Crop: 0.7, small diary: 0.5, Diary: 0.5, Pig: 0.1, Poultry: 0.9, Other: 0.4, all significant except poultry | Authors attributed the low rates of lung cancer to the lower consumption of smoke and to the different lifestyle of farmers |
| Cohort | 2,978 male farmers licensed to buy pesticides during 1971–1973 and their 2,586 wives from Viterbo, Italy. Follow-up: 1971–1996 | 46 | Identified from the regional registry using ICD-9 | General population of the region | Occupation | Age, sex | Male farmers: SMR = 0.54 (0.39–0.74), Wives: SMR = 0.67 (0.22–1.57) | Authors mentioned consistency with previous studies |
| Cohort | 6,310 female farm residents aged 30 to 64 year, registered in the NY Farm Bureau, or members’ spouses or relatives Follow-up: 1980–1993 | 21 | Identified from the local registry using ICD-9 | Women of same age living in rural areas of NY | Occupation | Age, sex | SIR = 0.33 (0.20–0.51) | Authors attributed the low rates of lung cancer to the low smoking among farmers |
| Cohort | 52,395 private pesticide applicators (97% men), 32,347 spouses (99% women) of them and 4,916 commercial applicators from Iowa and North Carolina, US. Recruitment: 1994–1997, Follow-up until 2002 | 346 | Identified from the national death index and local registries using ICD-9 | General population in each of the two states | Occupation | Age, sex | Private applicators: SMR = 0.47 (0.41–0.53). Commercial applicators: SMR = 0.59 (0.3–1.03). Spouses: SMR = 0.41(0.32–0.52) | Authors attributed the findings to lower smoking consumption and differences in lifestyle factors |
| Cohort | 52,392 private pesticide applicators (97% men) and 32,345 spouses (99% women) of them from Iowa and North Carolina, US. Recruitment: 1994–1997. Follow-up until 2000 | 158 | Identified from the national and local registries using ICD-9 | General population in each of the two states | Occupation, farm size (<200, >200 acres), Grew corn (yes, no), Had animals (yes, no) | Age, sex, state, race, smoking | Overall: SMR = 0.4 (0.3–0.4). Private applicators: SMR = 0.4 (0.3–0.4), Spouses: SMR = 0.3 (0.2–0.5). Stratified analysis SMR: Corn: 0.5 for no and 0.3 for yes, Animals: 0.5 for no and 0.3 for yes, Farm size: 0.3 for no and 0.3 for yes, all statistically significant | Authors attributed the findings to a HWE, to lower smoking and alcohol consumption, and to higher physical activity experienced by farmers compared to the general population |
| Cohort + nested case–control | Cohort: 2,916 male farmers from the province of Vicenza, Veneto region, Italy. Follow-up: 1970–1998 Case–control: 75 cases and 333 controls, all diary farmers | 75 | Diagnosed from the death certificates using ICD-9 | Cohort: The gen. male population of the region. Case–control: controls were systematically sampled | Occupation, tertiles of farm fields (<11, 11–21, >21) and diary cattle number (1–4, 5–13, >13). Time of quitting diary farm work (<15 year, >15 year) | Age, sex, smoking (case–control) | Overall: SMR = 0.64 (0.51–0.81). Cattle no: SMR = 0.76 (0.46–1.19), 0.37 (0.15–0.77), 0.26 (0.03–0.93) for the 1st, 2nd and 3rd tertiles. Case–control: Cattle no. OR = 0.60 (0.31–1.15) and OR = 0.18 (0.07–0.42) for the 2nd and 3rd tertile. Similar results for farm fields. Protective effect was removed for those that ceased diary farm work in more than 15 years ago | Authors concluded that increased levels of endotoxin (or other associated environmental factors) might be protective against lung cancer since protection diminishes over time after that exposure is removed |
| Cohort | All economically active Finns born between 1906 and 1945 who participated in the census of 1970 (667,121 men, 513,110 women). Follow-up: 1971–1995 | 270 | Identified from the national registry using ICD-9 | All the economically active population of Finland | Dust estimates obtained from the Nordic classification of Occupations (FINJEM). Exposure categorization: none, low, medium, and high for both plant and animal dust | Age, sex, social class, smoking | Reduced SIRs among those exposed to plant and animal dust (predominantly farmers), e.g., Animal dust: men: SIR = 1.03 (1.01–1.04), 0.89 (0.87–0.92), 0.92 (0.87–0.97), 1.22 (0.93–1.57), women: SIR = 1.01 (0.97–1.05), 0.95 (0.79–1.12), 0.93 (0.83–1.05), 0.46 (0.06–1.65) for the 1st, 2nd, 3rd and 4th group, respectively | Authors concluded that their results supported the hypothesis that exposure to animal and plant dust decreases the risk of lung cancer and that the stronger protective effect found in the highest exposure categories add to the hypothesis that endotoxin is responsible |
| Cohort | 143,863 (1,412 male and 416 female agriculture workers, 1,377 male, and 335 female farm operators and managers) workers aged >18 years who participated in the1987, 1988, and 1990–1994 US National Health Interview Surveys. Follow-up: 1986–2002 | 16 and 18 for farm workers and operators respect | Identified from the National Death Index using ICD-10 | All other occupational categories | General occupation (2 categories: (1) Farm workers and other agricultural workers and (2) Farm operators and managers), Specific occupation (Farm workers) | Age, sex, smoking | (1) Farm workers and other agricultural workers: Overall: OHR = 1.19 (0.74–1.89) Women: OHR = 1.14 (0.28–4.71) Men: OHR = 1.20 (0.63–02.29). Only farm workers: OHR = 0.91 (0.46–1.78) (2) Farm operators and managers: Overall: OHR = 0.83 (0.51–1.35), Men: OHR = 0.92 (0.59–1.44) | Due to the large number of occupations and the non-significant results, authors paid little attention to the agriculture populations |
Laakkonen and Pukkala [ 78] | Cohort | All Finnish farmers (87,534 men and 75,552 women) on Dec. 1978 still living on Jan. 1995 Follow-up: 1995–2005 | Still farming in 1990 or 1994: 352 Quit: 1443 | Identified from the Finnish Cancer Registry | General population of Finland | General occupation, farm type (crop, beef, dairy, pig, poultry, other) | Age, sex | Still farming in 1990 or 1994: SIR = 0.60 (0.54–0.66). Quit farming by 1990 or 1994: 0.73 (0.69–0.76) | Authors noted that farmers who changed production type from dairy to crop increased their overall cancer risk and tied this to the possibly protective effect of endotoxin exposure |
| Case–control | 499 (23 exposed to grain) lung cancer cases and 920 controls. All incidence male cases aged 35–70 selected from 19 hospitals of Montreal, Canada | – | Histologically confirmed identified from the hospitals’ pathology department records | Patients with other types of cancer selected from the same database | Industry (exposure to specific types of dust in two levels: non-exposed and substantially exposed) | Age, social, and economical status, race, smoking, accuracy of job history | Overall for grain (organic) dust: OR = 0.6 (0.4–1.1) | Authors were looking for potential carcinogens and thus did not comment the non-significant inverse associations between grain dust and lung cancer |
| Case–control | 733 (57 agriculture workers) lung cancer cases and 760 (39 agriculture workers) controls. All men aged 35–64 from Shanghai, China | – | Identified from the local registry using ICD-9 | Randomly selected from the local population | Occupation, duration (<10, 10–19, 20–29, >30 years) | Age, sex, smoking | Overall: OR = 1.6 (1.0–2.6) Duration: OR = 1.6, 1.6, 1.3 for <10, 10–19, 20–29 years of employment, respectively | Authors reported inconsistency with previous studies and mentioned that the use of pesticides might have altered the results |
| Case–control | 4,115 (346 farmers) cases and 10, 885 (1,374 farmers) controls. All men from Missouri, US during 1984–1988 | – | Identified from the Local registry using ICD-Oncology | Patients with other types of cancers selected with the same method | Occupation | Age, sex, smoking | Adjusted only for age: OR = 0.67 (0.60–0.76), adjusted for age and smoking: OR = 0.76 (0.66–0.86) | Authors mentioned consistency with previous studies but they concluded that differences in smoking habits do not explain the low lung cancer rates |
| Case–control | 4,224 (517 farmers) cases and 15,680 (2529 farmers) controls. All males aged >20 years from New Zealand | – | Identified from the national registry using ICD-9 | Patients with other types of cancers selected with the same method | Occupation (reference: non-farmers) and 4 types of farming: Livestock, diary, crop and general (poultry farm workers, etc.) | Age, sex | Overall: OR = 0.70 (0.63–0.77). Analyses by type of farming: Livestock: OR = 0.81 (0.57–1.13), Diary: OR = 0.66 (0.48–0.92), Crop: OR = 0.87 (0.64–1.18), General farmers: OR = 0.67 (0.60–0.75) | Authors attributed the demonstrated lower risk of lung cancer among farmers to the lower proportion of current and ex-smokers among farmers than in the general population |
| Case–control | 536 (107 farmers) lung cancer cases and 4,217 (1,023 farmers) controls. All men between 25 and 75 years from Alberta, Canada | – | Identified from the local cancer registry | Patients with other types of cancer from the same registry | Occupation | Age, sex, smoking, alcohol consumption | Crude: OR = 0.78 (0.62–0.97) Adjusted for age and smoking: OR = 0.81 (0.65–1.02) | Authors reported consistency and attributed the lower risk to the lower proportion of smokers among the farming population |
| Case–control | 508 (263 farmers) cases and 462 (274 farmers) controls, all male aged 35–80 years from Viterbo, Italy during 1980–1986 | – | Identified from the regional registry | Randomly sampled from the death registry | Occupation, duration (<10, >10 years), crop cultivation (wheat, crapes, olives, hazelnuts, fruits, potatoes, corn, strawberries) | Age, sex duration (only for type specific analysis) | OR: Overall: 0.76 (0.61–0.96). Duration: <10 years: 0.70 (0.52–0.93), >10 years: 0.81 (0.62–1.05). Cultivation: wheat, 0.79; crapes, 0.90; olives, 0.72; hazelnuts, 1.17; fruits, 0.88; potatoes, 1.18; corn, 0.92; strawberries, 0.89. All non-significant | The authors reported consistency with previous studies and suggested further investigation |
| Case–control | 686 (128 farmers and agriculture workers) cases and 712 (125 farmers and agriculture workers) controls, all German women | – | Histologically and/or cytologically confirmed | Randomly selected from the local population | Occupation | Age, region, smoking, time since smoking cessation | Farmers, agricultural workers: OR = 1.2 (0.88–1.72). Fishing, forestry, farming, and horticulture: OR = 1.3 (0.92–1.75) | Due to the large number of occupations included, authors focused on causal factors that showed significant elevated risks |
Pezzotto and Poletto [ 48] | Case–control | 367 (54 agriculture workers) lung cancer cases and 586 (66 agriculture workers) controls. All males from 3 medical institutions of Rosario, Argentina | – | Identified from the hospital records. All histologically confirmed and reviewed with ICD-O | Patients with non-smoking related diseases from the same hospitals | Occupation, duration (<33, >33 years) | Age, sex, smoking, and lifelong cigarette consumption | Overall: OR = 1.8 (1.1–3.1) Duration: OR = 1.1 (0.4–3.1) and OR = 1.9 (1.1–3.6) for <33 and >33 years of employment, respectively (p fro trend < 0.05) | Authors reported consistency with previous studies |
| Case–control | 24 cases (8 employed in farming) and 897 (229 employed in farming) controls. All females hospitalized in 3 regions of Italy during 1990–1992 | – | Identified from the hospital records; histologically and cytologically confirmed | Other cancer patients excluding those with Bladder cancer | Occupation, duration (1–9, 10–19, >20 years), 6 types of crops: wheat, vine, vegetables and fruit trees. Reference group: administrative staff workers | Age, sex, smoking, family history of lung cancer | Overall: 1.7 (0.7–4.4), Type: OR = 0.3 (0.1–2.0), 4.1 (0.7–24.0), 1.3 (0.1–1.6), and 2.5 (0.7–9.5) for wheat, vine, vegetable and fruit tree growers, respectively. Duration: OR = 1.0 (0.1–8.1), 1.0 (0.1–8.7), and 2.3 (0.8–6.6) for 1–9, 10–19 and >20 years, respectively | Authors mentioned inconsistency with previous studies that showed low risk of lung cancer and consistency with other studies in agricultural related populations. The low risk among wheat farmers was attributed to lower chemical use |
| Case–control | 216 (36 agriculture workers) lung cancer cases and 397 (66 agriculture workers) control subjects. All males from 4 hospitals of Buenos Aires, Argentina | – | Identified from the hospital medical records | Patients with non-smoking related diseases and neoplasms | Occupation, Job title (1 major title: agriculture and animal husbandry workers and 2 subtitles: Agriculture and Field crop workers) | Age, sex, hospital, pack-years, industries | Occupation: OR = 1.7 (1.0–2.8) Job title: agriculture and animal husbandry: OR = 1.6 (0.9–2.7), Agriculture: OR = 2.4 (0.9–6.1), Field crop workers: OR = 3.5 (1.1–10.5) | Authors reported consistency with previous studies |
| Case–control | 474 (50 exp. to grain, 32 to non-grain agriculture dust) men and 66 (5 exp. to non-grain dust) women lung cancer cases and 453 (48 exp. to grain, 22 to non-grain dust) men and 129 (15 exp. to non-grain dust) women controls. All from 88 hospitals of Leningrad, Russia | – | Pathologically diagnosed lung cancer cases identified from the hospital autopsy records | Deceased subjects with autopsy based diagnosis of non-cancer and non-smoking-related diseases | Industry (type of dust), duration (<10,>10 years), Average intensity (below or above 75% of the related MAC), cumulative exposure score (2 levels: <5 and >5 calculated as the product of average intensity score per total duration) | Age, sex, smoking, region of residence | Grain dust: Men: Overall: OR = 0.94 (0.60-1.46) Women: Non-grain agriculture dust: Men: Overall: OR = 1.24 (0.68-2.26). Women: Overall: OR = 2.43 (0.67-8.82) | As the analysis took place only to the overall level and due to the non-significant results, the authors paid little attention to the grain and to the non-grain agriculture dust |
| Proportionate mortality study | 254,901 deaths of males (28,032 farmers) in British Columbia, Canada Surveillance period: 1950–1978 | 742 | Identified from the provincial death registry using ICD-7 | Deaths due to the same cause in all non-farming occupations | Occupation | Age, sex | PMR = 0.66 (0.67–0.71) | Authors attributed the lower rates among farmers to the lower levels of alcohol consumption and smoking among farmers |
| Proportionate mortality study | 35,972 deaths of white male farmers aged >18 from Wisconsin, US. Surveillance period: 1968–1976 | 760 | Identified from the local registry office using ICD-8 | Deaths of males among all non-farmers in Wisconsin | Occupation | Age, sex, race | PMR = 0.52 (p < 0.05) | Authors attributed the lower rates among farmers to the lower levels of alcohol consumption and smoking among farmers |
| Proportionate mortality study | 2,820 deaths of male farmers aged 35 to 84 (1,415 whites and 1,405 non-whites). From South Carolina, US. Surveillance period: 1983–1984 | 198 | Identified from the state registry office using ICD-9 | 23,129 deaths of non-farmers during the same period and from the same area | Occupation | Age, sex, race | White: PMR = 0.80 (p < 0.05) Non-white: PMR = 0.87 (p>0.05) | Authors reported consistency with previous studies and attributed the lower rates among farmers to the lower levels of alcohol consumption and smoking among farmers |
| Proportionate mortality study | 119,648 deaths of white men, 2,400 of white women,11,446 of non-white men and 2,066 of non-white women. All farmers from 23 US states. Surveillance period: 1984–1988 | 7,218 | Identified from the regional registry | The proportion of deaths due to the same cause among non-farmers in the specific 23 US states | Occupation | Age, sex, race | PMR: 0.87 (0.85–0.89), 0.82 (0.62–1.06), 0.98 (0.90–1.05) and 0.60 (0.38–0.89) for white male, white female, non-white male and non-white female farmers, respectively | Authors attributed the lower rates among farmers to the lower levels of alcohol consumption and smoking among farmers |
| Proportionate mortality study + Case–control | All 21,186 cases of cancer among males reported to the ISCR during 1986–1988. (Complete information available only for 9,514). | 290 | Identified from the Illinois State Cancer Registry (ISCR) | Lung cancer among other occupations for both PMR and case–control | Occupation | Age, sex, race, smoking | PMR = 0.80 (p < 0.01) Case–control: OR = 0.71 (0.62–0.83) | Authors reported consistency with previous studies and concluded that other factors than smoking might also contribute to the low rate of lung cancer in farmers |
| Proportionate mortality study. | 88,090 deaths of white males aged >20 years from Iowa, US. Surveillance period: 1987–1993. | 1,412 | Identified from the Iowa State registry using ICD-9. | The proportion of deaths due to the same cause among non-farmers decedents. | Occupation | Age, sex | Overall: PMR = 0.70 (0.66–0.73) | Authors reported consistency and attributed the low rates to lower smoking and alcohol consumption by farmers |
| Proportionate mortality study. | 26,148 deaths of farm workers of 24 US states. Surveillance period: 1984–1993 | 1,546 | Identified from each State’s registry using ICD-9 | The proportion of deaths due to the same cause among all decedents in the specific 24 US states | Occupation | Age, sex, race | Overall: PCMR = 102 (97–107), White male: PCMR = 101 (94–107), White female: PCMR = 106 (97–116), Non-White male: PCMR = 124 (96–1570), Non-white female: PCMR = 79 (60–102) | Due to the many causes of death investigated and the non-significant results for lung cancer, authors paid little attention to these results |
| Proportionate mortality study | 229,549 and 44,930 deaths of crop and livestock US farmers, respectively. Surveillance period: 1984–1993 | Crop: 12,091 Livestock: 2,201 | Identified from the National occupational mortality surveillance using ICD-9 | The proportion of deaths due to the same cause among all database decedents | 2 types of farming: crop and livestock | Age, sex, race, smoking | Crop farmers: overall: RMR = 0.80 (0.78–0.81). Livestock farmers: PRM = 0.70 (0.67–0.73) | Authors considering also results from exposure assessment studies suggested that increasing exposure to endotoxin decreases the risk of lung cancer |